Mount and Blade is a wonderful game, however there is no point in purchasing this game - not long after this original release, Mount and Blade: Warband came out. It's largely the same game, using the same map and same general mechanics, but with the inclusion of multiplayer and achievements, as well as some general questline/mechanic improvements - it's basically the same game, but more. There's effectively no advantages this original game has over Warband, so it's not really worth purchasing. The one exception to this rule is that there were some mods created for it which did not get ported to Warband, so take a look at those via a Google search to see if one of them might be up your alley.
If you're trying to complete your library or support the developer/publisher? By all means. But if you're looking for the game to purchase, pick up Mount and Blade: Warband, instead.